Add tls.client_metadata_key support to vector source (and maybe http_server as well)

[vbr-cts]

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Use Cases

When sending logs between vector instances, it is currently possible to use TLS mutual authentication. The client and server will verify that they each have valid certificates. However, no information about this authentication is available for routing, remaping, or lua processing.

Having that information would mean we could then do authorization, or authenticate and track message origin.

Attempted Solutions

The socket source supports a tls.client_metadata_key option, that lets me do exactly what I need. However I then lose end to end acknowledgements.

Proposal

Add support for the tls.client_metadata_key option to the vector source. Ideally, it would also be added to the http_server source as well.

References

No response

Version

vector 0.38.0 (x86_64-unknown-linux-gnu ea0ec6f 2024-05-07 14:34:39.794027186)